1. Field of the Invention
The present invention relates to a cylinder lock and, more particularly, to a cylinder lock high in safety in various types of fields or applications. It is necessary to use a cylinder lock provided with an internal cylinder capable to be taken out of the mechanism of the cylinder lock when only a key to be exclusively used to exchange the internal cylinder opens or unlocks the cylinder lock, when the lock has to be exchanged by another lock with a different key code due to a missing key or the like,
2. Description of the Prior Art
Conventionally, when the key of the cylinder lock is lost, only a spare key has been preferably used in case it is not necessary to exchange the lock. However, in case it is necessary to exchange the lock for some reason following methods have been executed.
a method for exchanging all the lock PA1 a method for providing or preparing a lock for a customer and a lock for a manager for a lock device and removing an internal cylinder by the lock for manager PA1 a method for removing a lock in which an internal cylinder is integrated with an external cylinder in construction from a housing of the rock by the use of an exchanging master key.
Nowadays, there have been many accidents that a key is lost for a lock used in a lending locker for keeping clothes or belongings in golf links, a swimming pool, a fitness club or the like, a post office box, a lending safe, a multiple dwelling house or the like. Accordingly, in order to cope with this situation, a spare key has been frequently prepared.
In view of a crime prevention, however, it is not preferable to use the spare key. Thus, there has been a strong demand to exchange the lock when the key is lost.
When a method for exchanging a whole lock device is employed in order to meet this demand, there has been such a disadvantage as an amateur cannot work, nor cope with this work quickly, which results in producing an uneconomical problem.
The respective methods as set forth above that the lock for the customer and the lock for the manager are provided or prepared and the internal cylinder is removed by the lock for the manager, and that the lock in which the internal cylinder is integrated with the external cylinder is removed from the housing by the use of the exchanging master key are complicated in structure, so that they necessarily cause the cost of all the lock device to be high disadvantageously.
The present invention is proposed in view of these shortcomings and is designed to provide a cylinder lock simple in structure and capable of being produced in large quantities at low cost in which an internal cylinder can be simply taken out and exchanged only under an unlocked condition by means of a key only for exchanging the internal cylinder.